Buoy (15th century "boye"; through O.Fr. or Dutch, from Lat. boia, fetter; the word is now usually pronounced as "boy," and it has been spelt in that form; but Hakluyt's Voyages spells it "bwoy," and this seems to indicate a different pronunciation, which is also given in some modern dictionaries), a floating body employed to mark the navigable limits of channels, their fairways, sunken dangers or isolated rocks, mined or torpedo grounds, telegraph cables, or the position of a ship's anchor after letting go; buoys are also used for securing a ship to instead of anchoring. They vary in size and construction from a log of wood to steel mooring buoys for battleships or a steel gas buoy.

In 1882 a conference was held upon a proposal to establish a uniform system of buoyage. It was under the presidency of the then duke of Edinburgh, and consisted of representatives from the various bodies interested. The questions of colour, visibility, shape and size were considered, and any modifications necessary owing to locality. The committee proposed the following uniform system of buoyage, and it is now adopted by the general lighthouse authorities of the United Kingdom: -

Fig. 3. Spherical buoy with triangle. Fig. 3. Fig. 2. Can buoy with staff and cage. Fig. 2. Fig. 1. Conical buoy with staff and globe. Fig. 1.

(1) The mariner when approaching the coast must determine his position on the chart, and note the direction of flood tide. (2) The term "starboard-hand" shall denote that side which would be on the right hand of the mariner either going with the main stream of the flood, or entering a harbour, river or estuary from seaward; the term "port-hand" shall denote the left hand of the mariner in the same circumstances. (3)[1] Buoys showing the pointed top of a cone above water shall be called conical (fig. 1) and shall always be starboard-hand buoys, as above defined. (4)[1] Buoys showing a flat top above water shall be called can (fig. 2) and shall always be port-hand buoys, as above defined. (5) Buoys showing a domed top above water shall be called spherical (fig. 3) and shall mark the ends of middle grounds. (6) Buoys having a tall central structure on a broad face shall be called pillar buoys (fig. 4), and like all other special buoys, such as bell buoys, gas buoys, and automatic sounding buoys, shall be placed to mark special positions either on the coast or in the approaches to harbours. (7) Buoys showing only a mast above water shall be called spar-buoys (fig. 5).[2] (8) Starboard-hand buoys shall always be painted in one colour only. (9) Port-hand buoys shall be painted of another characteristic colour, either single or parti-colour. (10) Spherical buoys (fig. 3) at the ends of middle grounds shall always be distinguished by horizontal stripes of white colour, (11) Surmounting beacons, such as staff and globe and others,[3] shall always be painted of one dark colour. (12) Staff and globe (fig. 1) shall only be used on starboard-hand buoys, staff and cage (fig. 2) on port hand; diamonds (fig. 7) at the outer ends of middle grounds; and triangles (fig. 3) at the inner ends. (13) Buoys on the same side of a channel, estuary or tideway may be distinguished from each other by names, numbers or letters, and where necessary by a staff surmounted with the appropriate beacon. (14) Buoys intended for moorings (fig. 6) may be of shape and colour according to the discretion of the authority within whose jurisdiction they are laid, but for marking submarine telegraph cables the colour shall be green with the word "Telegraph" painted thereon in white letters.

Fig. 7. Diamond marker. Fig. 7. Fig. 6. Mooring buoy. Fig. 6. Fig. 5. Spar buoy. Fig. 5. Fig. 4. Pillar buoy. Fig. 4.